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Stars
There are a wide variety of stars in the galaxy which are classified by types and subtypes. A star system can have more than one star, some of which may not be used to refuel with a Fuel Scoop. A star is a giant ball of extremely hot gas (plasma), sustained by nuclear fusion which turns hydrogen into helium. All this energy produces heat, light and bigger chemical elements. A star emits electromagnetic radiation that moves away from the star as light. The large mass of a star holds it together. Old stars change helium into other elements like carbon and oxygen. Stellar Classification Each star or dwarf in Elite: Dangerous has an identifier for its classification which conforms to the Morgan–Keenan (MK) classification system. For example, the Sun of Sol has the classification identifier: G2 V Each identifier consists of three components: #Spectral class: A capital letter out of the sequence: O, B, A, F, G, K, M. (A helpful real-world mnemonic for remembering this is, "Oh Be A Fine Girl, Kiss Me.") This mainly specifies the temperature ranging from O'' (hottest) to ''M (coolest). Other letters specify extensions to this classification system, namely: W, L, T, Y, C, S,'' D.'' A few of those classes have subclasses such as'' DA, 'DB 'and 'DC 'as subclasses of' D.' #Spectral subclass: Each letter class is then subdivided using a numeric digit with '0''' being the hottest and 9'' being the coolest. #Luminosity class: A luminosity class is added to the spectral class using Roman numerals.This classifies the stars by its spectral characteristics considering color and brightness. Those spectral characteristics provide information about the type of the star: *''I for supergiants **''Ia'' or 0'' for hypergiants or extremely luminous supergiants **''Iab for normal supergiants **''Ib'' for less luminous supergiants *''II'' for bright giants *''III for regular ''giants *''IV'' for sub-giants *''V'' for main-sequence stars (''most of the known stars belong to this class) **Va'' for extremely luminous main sequence stars **''Vab'' for luminous main sequence stars **''Vb'' for normal main sequence stars **''Vz'' for less luminous main sequence stars *''VI'' for sub-dwarfs *''VII'' for white dwarf Thus, G2 V means: The Sun is semi hot (G), it belongs to the hotter stars (2) in class G and it is considered as a so called main-sequence star (V). Star Types Main Sequence Stars (O, B, A, F, G, K, M) With a ratio of ~77%Rarity in relation to all stars (34 million in total), according to https://www.edsm.net on 10 Aug 2019. The usual disclaimers about bias(es) apply. of all stars this category can be considered Very Common.Based on the following thresholds: <1% Very Rare; 1-5% Rare, 5-10% Uncommon; 10-30% Common; >30% Very Common Giants and Supergiants With a ratio of ~0.25% of all stars this category can be considered Very Rare. Proto Stars (Herbig Ae/Be, TTS) With a ratio of ~2.4% of all stars this category can be considered Rare. Carbon Stars (C, CH, CHd, CJ, CN, CS, MS, S) With a ratio of ~0.08% of all stars this category can be considered Very Rare. Wolf-Rayet Stars (W, WC, WNC, WNC, WO) With a ratio of ~0.05% of all stars this category can be considered Very Rare. Black Holes With a ratio of ~0.41% of all stars this category can be considered Very Rare. Neutron Stars With a ratio of ~4.0% of all stars this category can be considered Rare. White Dwarves (D, DA*, DB*, DC*, DO*, DQ, DX) With a ratio of ~0.36% of all stars this category can be considered Very Rare. White dwarfs (category D for degenerate) are the collapsed core of a star that has lost a large proportion (~20%) of its original mass as the ejected material of a planetary nebula or in a supernova explosion, the terminal stages of stellar evolution. White dwarfs are not stars because they no longer sustain nuclear fusion, and lacking this interior thermal source of support the star has gravitationally collapsed to a very small radius. White dwarfs glow with the residual heat of the degenerate core, which can have a temperature well above 100,000 K at collapse and that cools over several billion years. Class D is further divided into spectral typeshttp://www.handprint.com/ASTRO/specclass.html that indicate the elemental composition of the photosphere. * DA: strong Balmer series hydrogen absorption lines only; no helium or metals present. * DB: strong He I (neutral helium) absorption lines only; no hydrogen or metals present. * DC: a continuous (blackbody) spectrum with no absorption lines deeper than 5% in any part of the electromagnetic spectrum. * DO: strong lines of He II (ionized helium) with molecular hydrogen or helium present. * DQ: carbon absorption lines, either atomic or molecular, in any part of the electromagnetic spectrum. * DZ: metal (elements heavier than helium) absorption lines in the absence of both hydrogen and helium lines. Symbols Appended to the Above Designations * P: magnetic white dwarfs with detectable polarization. * H: magnetic white dwarfs without polarization. * X: peculiar or unclassifiable spectrum. * E: emission lines (of any element) present. * ?, :: uncertain classification. * V: variable luminosity. * d: circumstellar dust. * C I, C II, O I, O II added within parentheses to indicate the presence of these elements in DQ objects. The current practice is to append numerical indicators of the white dwarf temperature and surface gravity, separated by an underline "_". Temperature is indicated as the effective surface temperature divided into 50400 and rounded to the first decimal place, e.g. DA.9 = 56000 K and DB1.2 = 42000 K. Gravity is assessed as the width of the dominant spectral lines and the log values range from 7 to 9. The table below shows the white dwarf subtypes within Elite Dangerous. These do not necessarily match the notation mentioned above (for example, ED uses DAZ which probably should be DZ) but comes very close. The "Rarity" column indicates the subtype rarity within the White Dwarves spectrum. Brown Dwarves (L, T, Y) With a ratio of ~15% of all stars this category can be considered Common. Undiscovered Star Types These classes are mentioned in the Journal documentation, but none have been submitted to EDSM yet. Largest Stars Some of the largest and most well-known stars in the galaxy are listed below, from smallest to largest. They are ordered by solar radius which is the unit of measurement based on the radius of the sun in Sol (695,700 km; 432,288 mi). *Proxima Centauri (within the Alpha Centauri system) *Wolf 359 *Sol (sun) *Sirius *Pollux *Arcturus *Aldebaran *Rigel *Antares *Betelgeuse *Mu Cephei *VV Cephei A *VY Canis Majoris The largest known star within 10k ly from Sol is Eta Carinae, located 7500 ly from Sol. The larger of the two stars weighs in at ~90 solar masses. It has a companion at ~30 solar masses (estimates are variable) and they are 750 ls apart at periastron. UY Scuti and NML Cygni are not included because back in 2013 when the game's galaxy was being crafted, the diameter of UY Scuti had not yet been measured and reported in the popular astronomy press. At that time, VY Canis Majoris was "the largest star in the known galaxy". A more comprehensive list of the largest stars recorded in Elite Dangerous is available at Elite Galaxy Online and the Universal Cartographics Record Book. Videos File:Elite_dangerous_4._Suns File:Elite_Dangerous_Timelapse_Sparks_Of_The_Galaxy_1 File:Elite_Dangerous_Beta_3.3_-_World_of_death_-_SPOIHAAE_XE-X_D2-9 File:Elite_Dangerous_-_DRIFT References Category:Celestials Category:Guides Category:Stars